Universal joints

ABSTRACT

A universal joint is disclosed which is made primarily of plastic. A center cube of the joint has two pairs of opposed rod ends. The arms of bifurcate members may be molded directly about the rod ends, or on a bearing mounted about the rod ends. The bifurcate members may be all plastic or plastic-covered steel. The center cube and rod ends may be molded as one integral plastic unit or, if desired, the rods may be made of steel with the center cube made of plastic and molded about the rods.

United States Patent Williams 5] May 16, 1972 {54] UNIVERSAL JOINTSFOREIGN PATENTS OR APPLICATIONS [72] Inventor: Ralph Williams, Coventry,England 550,332 10/1956 Belgium ..64/17 963,249 7/1964 Great Britain..64/l7 [731 Assgnefi The 1,152,958 2/1958 France ..64/1 7 Coventry,England [22] Filed: June 30, 1970 Primary ExaminerEdward G. FavorsAttorney-Carl R. Horten, David W. Tibbott and Frank S. [21] Appl. No.:51,102 Troid] 30 Foreign Application Priority Data [571 ABSTRACT July 41969 Great Britain ..33 807/69 A universal is discbsed which is madePrimarily 0f plastic. A center cube of the joint has two pairs ofopposed rod 52] ends. The arms of bifurcate members may be moldeddirectly [5]] about the rod ends, or on a bearing mounted about the rodends. The bifurcate members may be all plastic or plastic- [58] F ieldof Search ..64/ l 7 covered steel The center cube and rod ends y bemolded as one integral plastic unit or, if desired, the rods may be madeof [56] References cued steel with the center cube made of plastic andmolded about UNITED STATES PATENTS the rods- 2,844,949 7/1958 Stillwagon..64/1 7 5 Claims, 6 Drawing Figures UNIVERSAL JOINTS This inventionrelates universal joints.

A common form of universal joint comprises a pair of mutuallyperpendicular rods or pins extending from a central carrier member,often in the form of a cube and a fork or the like bifurcated memberattached to the ends of each rod, the forks permitting a pair of shaftsthrough which power is to be transmitted to be flexibly connected to oneanother even though there may be some degree of misalignment between theshafts. Usually a roller bearing is interposed between each arm of thefork and the region of the rod to which it is connected.

It will be appreciated that the assembly of a universal joint comprisinga plurality of components as described above is quite complex and timeconsuming and the invention accordingly seeks to provide a universaljoint which overcomes or at least reduces this disadvantage.

According to its broadest aspect, the present invention provides auniversal joint in which a center piece is molded, in a plasticsmaterial, integrally with rod portions extending mutuallyperpendicularly from said center piece and in which forks also formedfrom a plastics material are subsequently molded around the integralcenter piece and rod component.

By virtue of the invention, therefore, the assembly of separate rodsinto a center piece and the provision of individual bearings between therods and the co-operating fork arms are eliminated and a universal jointof simplified construction and economic manufacture results. Theplastics materials used in the molding process may, for example, benylon or polytetrafluoroethylene and may be reinforced if desired withglass fibers or carbon fibers. It will be appreciated that the forksneed not be molded from the same material as the integral center pieceand rod assembly.

According to another feature of the invention, instead of molding therod portions integrally with a center piece, a center piece may bemolded around a previously assembled perpendicular rod arrangement andin such a case the rods may, of course, be of a metal such as steelrather than of a plastics material. Conveniently, rod components forassembling together to constitute the perpendicular rod arrangement mayeach be centrally recessed or rebated with the recesses or rebatesdimensioned so that two such rod components may be clipped together andif desired may thereafter be secured together by passing a suitable pinthrough them.

Where bearings are interposed between the rods and the fork armsconnected to them, the method of assembly may be such that the forks aredirectly molded on to the bearings which themselves have been previouslyassembled on to the rod ends.

The invention will be further understood by reference to the followingdetailed description and drawings, in which:

FIG. I is an elevation, partly in exploded perspective of a center piecefor use in a universal joint;

FIG. 2 is a median section through part of a conventional universaljoint;

FIG. 3 is a similar section through part of a universal joint embodyingthe invention;

FIG. 4 is a perspective view of a rod component for use in a universaljoint according to the invention;

FIG. 5 illustrates the rod component of FIG. 4 assembled with acomplementary component; and

FIG. 6 is a perspective view partly in section of a bifurcated memberhaving a steel core;

Referring firstly to FIG. 1, a center piece for a universal joint willbe seen to comprise a cube 10 having two pairs of opposed rod ends 12extending from opposed faces of the cube. The center piece isillustrated as carrying a needle bearing 14 on each rod end 12.

In a conventional universal joint, the cube 10 is often manufacturedfrom steel, bored to receive either four rod ends or alternatively oneintegral rod situated in a through bore in the cube, with a pair ofopposed rod ends located in perpendicular faces of the cube. When suchan assembly is complete, it is then necessary in a conventionaluniversal joint to fit the needle bearings on to the projecting rodends. Thereafter, as shown in FIG. 2, it is necessary to connect thethrust transmitting forks to their respectively co-operating rod ends. Apart of one such fork 16 is shown in FIG. 2 and will be seen toterminate in an arm 18 having its end region apertured at 20 to receivethe outer race 22 of a needle bearing generally designated 24. It iscustomary to retain the bearing 24 against outward displacement in theaperture by means of a clip 26. Due to this arrangement, however, thereis a depth D of the aperture 20, lying substantially between the clip 22and the free outer face of the arm 18, which cannot usefully contributeto the supporting of the outer race 22 of the bearing.

In accordance with one feature of the present invention, as shown inFIG. 3, a fork 28 is molded around a center piece 10, the rod ends 12 ofwhich have previously been fitted with bearings 30. In the conventionalbearing illustrated in FIG. 2, the space D remains because it is neededfor manipulation during assembly, when the bearing 24 is pushed throughthe aperture 20 which has previously been positioned in a jig over therod end 12. In the bearing proposed by the invention and shown in FIG.3, because the forks 28 are molded over the previously assembled centerpiece and bearing arrangement, the arms 32 of the fork 28 are shaped ina mold around the bearing outer race 34, there is no requirement for anymanipu lative space to be left to accommodate the bearing assembly, thebearing is retained in the fork arm- 32 by an integrally molded blindend 36 of that arm and therefore the bearing 30 is supported over a muchgreater depth, only the thickness d of the end 36 being lost for thispurpose.

As will be appreciated, the assembly comprising the center cube 10 androd end 12 of FIG. 1 may be molded in a plastics material as an integralassembly. In that case, where both the rod ends 12 and, for example, thefork arms 32 of FIG. 3 are made of suitable thermoplastics materials, itis unnecessary for some applications to employ roller bearings at alland the forks 28 may then be themselves molded directly over thepreviously molded center piece and rod end components.

Where it is desired to employ center pieces using separate rods, apreferred rod configuration is illustrated in FIG. 4 which shows a rod38 as having a central recess 40, the depth of which is approximatelyequal to the radius of the rod 38. The width of the recess 40 iscommensurate with the diameter of the rod 38. FIG. 5 illustrates how twosuch rods 38 may then complement each other and may be clipped togetherin mutually perpendicular arrangement in which, if desired, they may besecured by passing a securing pin centrally through them. Theperpendicular rod arrangement 'of FIG. 5 may thereafter be placed in amold to have a center cube l0 molded around it and may subsequently beused in any of the embodiments of the invention herein described. Inorder to permit the relief of pressure build-up inside the bearings whenthe material is being molded around them, each rod 38 is shown as havingan axial hole 42 running throughout its full length and the holes 42communicate with cross drillings 44. The same axial holes and crossdrillings serve to permit lubrication or re-lubrication of the bearingsafter the complete unit has been manufactured.

Another embodiment of universal joint fork forming part of my inventionis disclosed in FIG. 6. The fork comprises a steel pressing'50 which isencased in plastic 52. The shape of the steel pressing 50 is the same asthe shape of the plastic 52 except, of course, the dimensions of theplastic 52 are larger than the dimensions of the steel pressing 50.

The fork is made by dropping the steel pressing into a mold prior to theactual molding operation so that during the latter, plastic materialflows around the pressing. This provides a fork for a universal jointwhich is basically plastic but which will still have a resilient steelcore should excessive overload or other abuse cause the plastic tofracture.

Iclaim:

1. A universal joint comprising:

a central member;

two pairs of opposed rod ends extending from the central member; and

bearing is mounted about each rod end; and the arms of the bifurcateplastic members are molded about the bearings.

3. A universal joint in accordance with claim 1, wherein the centralmember and rod ends are integral and made of plastic material.

4. A universal joint comprising: a central member; two pairs of opposedrod ends extending from the central member; and

bifurcate plastic members having their anns molded about the rod ends,wherein the central member and rod ends are integral and made of plasticmaterial.

5. A universal joint comprising:

a central member;

two pairs of opposed rod ends extending from the central member; and

bifurcate plastic members molded about the rod ends with each arm of thebifurcate plastic members having a bore extending almost entirelythrough the arm thus providing a blind end, said rod ends extendingsubstantially entirely into the bores wherein the central member and rodends are integral and made of plastic material.

1. A universal joint comprising: a central member; two pairs of opposedrod ends extending from the central member; and bifurcate plasticmembers having their arms molded about the rod ends and a steel core ofsubstantially the same shape as the outer plastic covering of theplastic member.
 2. A universal joint in accordance with claim 1, whereina bearing is mounted about each rod end; and the arms of the bifurcateplastic members are molded about the bearings.
 3. A universal joint inaccordance with claim 1, wherein the central member and rod ends areintegral and made of plastic material.
 4. A universal joint comprising:a central member; two pairs of opposed rod ends extending from thecentral member; and bifurcate plastic members having their arms moldedabout the rod ends, wherein the central member and rod ends are integraland made of plastic material.
 5. A universal joint comprising: a centralmember; two pairs of opposed rod ends extending from the central member;and bifurcate plastic members molded about the rod ends with each arm ofthe bifurcate plastic members having a bore extending almost entirelythrough the arm thus providing a blind end, said rod ends extendingsubstantially entirely into the bores wherein the central member and rodends are integral and made of plastic material.